Heretofore, for window glasses for automobiles, ones having various curved shapes accommodated to designs of automobiles, are employed. These window glasses are produced by cutting a plate-shaped glass sheet produced by e.g. a float method into a desired shape, heating and softening it and bending it by e.g. a press-forming. For side glasses or rear glasses, a tempered glass is commonly used, and by immediately air-cooling a heated glass sheet after bending, a so-called physically tempered glass is produced.
Meanwhile, a laminated glass to be employed for windshields is produced by placing two glass sheets cut out to have substantially the same shape, on a ring-shaped jig so that they are overlaid, and heating them to be bent into a desired curved shape by their own weight. After the bending, they are gradually cooled without being air-cooled for tempering, as in the case of tempered glass. Thereafter, an interlayer (such as polyvinyl butyral) is sandwiched between the bent two glass sheets, a preliminary pre-pressing treatment in a vacuum bag and subsequent heating and pressurizing treatments in a autoclave are carried out to produce a laminated glass in which the glass sheets and the interlayer are laminated.
When a curved glass thus produced is assembled into an automobile, high shape reproducibility is required. In a case of door glass which is slidable up and down by an operation of a driver/passenger to close or open the window, if a predetermined design shape of the glass is not produced, the glass may be collided or frictioned with e.g. metallic members to be damaged when it is slid. Further, in a case of fixed window such as an windshield or a rear glass, if the reproducibility of the shape is poor, it becomes difficult to attach the glass to an opening, and see-through distortion (a phenomenon that an image through a glass is distorted) or a reflection distortion (a phenomenon that an image reflected by a glass surface is distorted) may occur as problem unique to window glasses.
To cope with these problems, heretofore, a glass sheet after bending has been placed on an inspection apparatus (refer to e.g. Patent Document 1) called as a gauge to carry out shape inspection, and only glass sheets having a predetermined shape accuracy have been employed for production of automobiles. Such a gauge is an inspection mold having a placing plane formed so as to fit to a predetermined design shape, and a plurality of distance sensors are embedded in the placing plane. By measuring the distance from the surface of the mold to a rear surface of a glass sheet, displacement of the shape of the glass sheet from its design shape, is measured to evaluate the accuracy of the shape. Heretofore, an inspection using such a gauge has been carried out with respect to all or sampled formed glass sheet.
Patent Document 1: JP-A-4-242103